@AlyaB: As the issue occurred after you'd been abroad, have you tried reaching out to your network to see if the feature is still active on your account? If it is, try heading to Settings > Connections > More connection settings > Rich communications, and toggle this option on if applicable. Now, if you're using the Samsung Messages app, head to the app > Tap the 3 dots in the top right > Settings > Chat settings > Chat features > On > Default message type > Automatic. Let me know how you get on.
